Once the digital files have
been created, they need to be stored and managed in a way that makes them
available for use via the access mechanism decided on for the project and
ensures their preservation for the period of access required. Two main issues to
be considered are:

software or file format
structure which will be used to house the files, and

Unlike physical media,
digital media cannot be accessed without computer hardware and software. It is
also vulnerable to destruction if the magnetic or optical media it is stored on
is corrupted. An appropriate data management strategy is therefore critical to
the on-going viability of a digital collection.

It is important to consider
the IT infrastructure which is available to assist with the digitisation
project. If in-house IT staff and equipment are to be utilised, they may require
additional funding to cover the increased workload and/or equipment
requirements. Additional training may also be necessary in specific areas of
expertise connected with digitisation. If IT support is to be outsourced, this
must be properly costed and documented to ensure that both sides have the same
understanding of the level of support which is to be provided. IT problems can
often become larger or more complex than expected and parties on each side of an
agreement should be aware of how they will deal with this if it should
occur.

Costing
issues

The cost of storage and
management of digital data is highly dependent on the IT infrastructure used,
the volume of data to be stored and the level of data protection required.
Approaches which leverage off existing arrangements for storage of data - such
as the library's integrated library management system (current systems often
include a module for storage of image data) or a Local Council's document
storage system - are likely to be more cost-effective than something instituted
to serve the digitising operation alone. A central approach to data storage,
whether outsourced to a commercial organisation or managed collaboratively, is
also likely to create economies of scale for small-scale digital collections. It
is important to obtain professional IT advice on the appropriate storage
requirements for the project.

File naming protocols

Documented file naming
protocols are imperative for any digitisation project. The digital files which
are created will need to be named so that they can be meaningfully linked to the
appropriate metadata and access mechanisms and the files can be located easily
for future management. A naming protocol which is meaningful to humans may be
appropriate in a small collection where files will be managed manually. However
in collections of tens or hundreds of thousands of items, files are more likely
to be subject to some form of automated management and therefore file names
which are meaningful to the computer system may be more appropriate. This is a
decision which will be specific to each project, however if interoperability is
a desirable outcome, it may also be dependent on protocols being used in other
systems.

Whatever protocol is chosen
it should be clearly documented. If a mechanism for automatic generation is
used, for example using existing thesauruses, there are likely to be fewer
misnamed (and therefore possibly permanently lost) files. The State Library of
Victoria uses an 8 character file name with the first 2 alphabetical characters
refer to the collection and the final 6 numerical characters are a sequential
number. Consideration should be given to the effect of using leading zeros
before sequential numbers if later items may need to be inserted into the
sequence for any reason.

Storage
mechanisms

There are a number of
options for storage of digital files, however the main storage options are:

flat-file storage on a server

proprietary image databases

more complex digital object management systems

outsourcing to an external agency

Digital files may require a
large amount of computer disk storage space, particularly if high quality master
files are being stored. A photograph may take up tens of megabytes of storage
space if it is in high resolution uncompressed TIFF format. However the same
photograph may only take up a few hundred kilobytes if it is in lower resolution
JPEG format. In a collection of hundreds or thousands of digital items, storage
can be a substantial cost. However the cost of disk storage is constantly
decreasing and tape or CD-ROM storage may offer an alternative for material
where instant access is not required. Storage can also be outsourced to
companies who specialise in data storage.

Flat-file storage

This is often the default
option for digital projects, as local servers can easily be made available and
web site managers are familiar with the storage of image files in file
structures on these servers. For a small number of files this may be an
appropriate option. The system requires some manual management of the files and
if this is undertaken by an administrator unfamiliar with the specific files,
does allow the possibility of loss or damage of data.

Proprietary image
databases

There are a number of image
databases on the market now, many of which will store a wide range of digital
file types. They may also offer additional functionality such as version control
of changes made to files, multiple format storage or automatic generation of
lower resolution copies of images, workflow management, user access
authentication and cataloguing. The database architectures underlying these
proprietary systems will be one of three basic types. These are: 'flat-table'
(in which data is held as a series of single 'card file' type entries);
'relational' (where data is held in tables and relationships are specified
between the data); or 'object-oriented' (the next generation, where data is
represented as a complex object which can have attributes and operations
performed upon it). The software systems available will therefore range from
very simple databases which may allow in-house customisation, to professional
digital object management systems. Some databases which appear simple and easy
to use, may not have the flexibility required for a more complex project. Any
choice of database will depend upon the specific requirements of the project or
collection. The issue should not be decided without seeking professional IT
advice.

Complex digital object
management systems

Many large libraries and
museums have developed complex software and hardware architectures to house
digital files and associated metadata. This is a very specialised area and
generally well beyond the resources of smaller organisations. However
examination of such systems can provide valuable information on developing
technologies such as SGML/XML which may be used more widely in the
future.

Outsourcing

Data management can also be
undertaken by an external agency specialising in data management. Data can be
stored off-line on either magnetic (tape or disk) or optical (CD-ROM) storage
and only delivered to users on request. Alternatively it can be stored on a
server computer which is online and allows 24 hour 'live' remote access. Even if
data is stored by an external agency, interface design can make it appear to
users that it is all being delivered from the one collection.

For further information on
image management systems see Kenney & Rieger, 119.

Data
management strategies

However the data is stored,
it is imperative that an appropriate data management strategy is in place to
ensure ongoing access to the items. This should include appropriate and robust
back-up systems including off-site storage of one copy at all times.

Long-term storage of digital
files is fraught with difficulty due to the rapid changes in hardware and
software. There are three possible solutions currently advocated for ensuring
long-term access to digital data:

Technology preservation (keeping original versions of outdated hardware and software)

Emulation (using modern versions of hardware and software to 'pretend' they are operating like
outdated versions)

Migration (transferring
data onto newer hardware and software as old versions are outdated)

Increasingly the third
option is being seen as the most realistic. (Lee 146) It is also important to
regularly refresh data by periodically copying files onto new storage media, as
magnetic storage media (tape and disk) has a finite life span. However for long
term management, it will also be necessary to have in place a data migration
plan. This will need to ensure that at appropriate times data is transferred to
new file formats which can be accessed by current hardware and software. This
will prevent the risk of data being held in outdated file formats and possibly
becoming unreadable at some stage in the future.

Security

Consideration should be
given to both security of the actual data, including proper back-up and data
migration strategies, and security of the intellectual property contained within
the data.

To protect the intellectual
property in the data it may be necessary to restrict access in some way and/or
to embed security information into the file itself. A number of cultural
organisations have placed visible or invisible watermarks into their digital
images in order to protect against unauthorised further use of the image. A
number of companies sell watermarking technologies and this is a rapidly
changing field. For an example of the use of watermarks, see the Australian War
Memorial site which includes visible watermarks on many of its photographic
images in order to prevent unauthorised reproduction. (see examples at http://www.awm.gov.au)

Watermarking technologies
are 'far from stable' and can be expensive to implement and may not necessarily
be totally effective. (Lee, 144)

It may also be appropriate
to restrict access to the collection using password protection or some other
form of access authorisation. Any decision made in this area will be highly
dependent upon both copyright restrictions and management or business plans for
the collection. It is likely to be necessary to seek professional IT assistance
to establish the appropriate security strategies for your project.

Archival
preservation

There is still considerable
debate regarding the appropriateness of digitial technologies for long-term
preservation. Although digitisation may assist with the preservation of
originals by reducing the use of fragile physical items, there is considerable
risk that digital information itself will become non-accessible in a relatively
short space of time due to degradation of storage media and/or upgrading of
hardware, software and file formats.

Loss of access to material
can be caused by the degradation of the storage media, loss of functionality of
the access devices, loss of manipulation and presentation functions, or the
disfunction in the documentation chains. The challenge in the preservation of
digital material is to retain the essence of the original material by
maintaining its function, content and context. http://www.swin.edu.au/afi/digital%20preservation.pdf

A digitisation project
should not consider preservation as one of its goals unless there has been
considerable planning and research into the long-term viability of all technical
and management processes put in place. Digital preservation should not be
attempted without expert advice from both archival and technical
experts.